Coventry Crown Court heard how Keown, who has two previous convictions for indecent assault, had brain surgery for skull injuries suffered in a fall in his youth, which had left him susceptible to impulsive behaviour.

Glyn Samuel, prosecuting, said on January 3 the teenager followed a woman in the car park at the Caludon Centre, at Walsgrave Hospital.

He grabbed her breasts, pushed her to the ground, and asked if he could have sex with her while continuing to indecently assault her.

Mr Samuel said: "She was extremely frightened and distressed. She began to scream as you would expect. She believed she was going to be raped."

The court heard Keown had been sentenced to two year detention in November 2000 for an indecent assault on a 12-year-old girl in a social club car park.

He had also been convicted of a indecent assault on a female member of a youth offending team.

Keown appeared for sentencing after a request for presentence and psychiatric reports.

Peter Haynes, defending, said: "As an 11-year-old he was a bright and promising young child until a terrible accident.

"He is somebody who plainly needed help but who was without help when this offence was committed."

Sentencing Keown to four years in a young offenders institution, Judge Bruce Coles said: "It seems to me that this is one of those cases where your own personal circumstances...have to take second place behind the duty of the court to protect victims from sexual attacks."